Synthesis, crystal structures and electronic properties of isomers of chloro-pyridinylvinyl-1H-indoles

► Three chloro-indolic isomers were synthesized and evaluated on hTDO. ► The single-crystal X-ray analyses of two of them revealed non-planar structures. ► The position of the Cl atom does not notably affect the electronic delocalization. ► The non-coplanarity plays a more important role in the crystalline packing. ► Physico-chemical properties led to an understanding of mechanism of TDO inhibition.